To more efficiently transmit digital audio data on low bandwidth data networks, or to store larger amounts of digital audio data in a small data space, various data compression or encoding systems and techniques have been developed. Many such encoded audio systems use as a main element in data reduction the concept of not transmitting, or otherwise not storing portions of the audio that might not be perceived by an end user. As a result, such systems are referred to as perceptually encoded or "lossy" audio systems.
However, as a result of such data elimination, perceptually encoded audio systems are not considered "audiophile" quality, and suffer from processing limitations. To overcome such deficiencies, a method, system and product have been developed to encode digital audio signals in a loss-less fashion, which is more properly referred to as "component audio" rather than perceptual encoding, since all portions or components of the digital audio signal are retained. Such a method, system and product are described in detail in U.S. patent application Ser. No. 08/771,790 entitled "Method, System And Product For Lossless Encoding Of Digital Audio Data", which was filed on the same date and assigned to the same assignee as the present application, and is hereby incorporated by reference.
Many broadcasters use analog or non-perceptual modes of enhancing and processing audio for clarity of broadcast or recording. Such conventional methods add even numbered harmonics in the analog domain or in a digital signal processor implementation thereof. Unfortunately, such methods also add odd harmonics (such as #3, #5, #7, etc.) that are discordant or audible as distortion, since distortion is the method used to implement such methods. In the digital perceptual signal path, however, no such processing exists.
Thus, there exists a need for a method, system and product for harmonic enhancement of encoded audio signals, particularly perceptually encoded audio signals. Such a method, system and product would add synthetic harmonics at octave intervals to perceptually encoded audio signals, thereby adding clarity to the signals and/or compensating for low audio bandwidth.